2,7-Dibromofluorenone is a substance useful as a raw material for agrichemicals, medicines, high functional polymers, dyes, pigments, and photosensitizers. Oxidation of 2,7-dibromofluorene is known to be able to produce 2,7-dibromofluorenone.
Conventionally-known processes for the production of 2,7-dibromofluorenone from 2,7-dibromofluorene include oxidation with a chemical such as chromic anhydride, nitric acid, potassium permanganate or potassium dichromate. Such chemical oxidation, however, involves problems in health and environment in addition to a problem in productivity, and therefore, is not suited for the industrial production of 2,7-dibromofluorenone (see JP 58-177955 A).
On the other hand, a process is known to produce 2,7-dibromofluorenone by reacting 2,7-dibromofluorene and p-dimethylaminonitrosobenzene in ethanol in the presence of metallic sodium or potassium cyanide as a catalyst (see N. Novelli, Anales asocn. quim. Argentina, 25, 187 (1927)). According to this process, a byproduct is reacted further in the presence of metallic sodium catalyst in a mixture of the raw material, 2,7-dibromofluorene, and ethanol to produce 2,7-dibromofluorenone. However, these catalysts are all costly and difficult in handling so that the above-mentioned process is not considered to be a practical process.
In other words, the above-described conventional processes are different from the process of the present invention which will hereinafter be described in detail, because the former processes are each different in the reaction system or the catalyst component from the latter process. From the standpoint of economy, the conventional processes are not fully satisfactory.